If you find a source, list it here with all the info you can, links, description, price, part number etc.
http://www.cumminsfiltration.com
http://www.donaldson.com
i tried something that i had laying around
it was an aircleaner assembly off a horizontal b&s 16 hp engine, the one that is sitting atop the down tube
to the carb, about 6inches in diameter.
the element i replaced was from napa and is very well supported by expanded metal inside and out, pleated paper construction
interestingly it really kills the intake noise from the little changfa, something i did not expect at all!
those aircleaner housings ought to be available anywhere mowers and small engine's are repaired for cheap and iirc the element was less than 10 bucks.
my goal was something to use for testing, as it turns out i can see replacing it with anything else.
fwiw
bob g
http://www.solbergmfg.com
Intake noise reduction